body {
  margin: 0;
  padding: 0;
}
.page {
  width: 100%;
  height: 100vh;
  padding: 10px;
  box-sizing: border-box;
  display: grid;
  grid-template-columns: 1fr 200px;
  grid-gap: 10px;
}
.page .content {
  height: 100%;
  overflow: hidden auto;
}
.page .content::-webkit-scrollbar {
  display: none;
}
.intro p {
  text-indent: 2em;
}
.demonstration {
  width: 100%;
  padding-top: 30px;
  margin-bottom: 10px;
  border: 1px solid #cccccc;
  position: relative;
  box-sizing: border-box;
}
.demonstration::after {
  content: "效果展示";
  display: block;
  line-height: 30px;
  width: 100%;
  position: absolute;
  top: 0;
  left: 0;
  padding-left: 1em;
  background-color: #cccccc;
}